This is the only good RPN calculator app I found.
Not exactly the answer you’re looking for, but here’s some info about Reverse Polish Notation…
Just use some HP calculator emulator. That way you don’t have just an RPN calculator, but a full fat graphing calculator.
I’ve been using Droid48 forever. It’s perfect.
Realcalc has an excellent RPN mode (enabled through Calculator Type in Settings). I’ve used it for the last six years or so (technically, in the premium version of the app).
Edit: Not open source - sorry, didn’t see the community!
I’m using this one and am very happy with it.
It has not been updated since a year.
It works as well as on the first day I started using it, so I don’t really mind.
What has changed about RPN or calculators in the past year?
Android had changed.